In the known process a deep drawable composite thermoplastic foil with a PVDC layer is subjected to a deep drawing process at a definite temperature and the container is formed by the deep drawing process. By "PVDC" I mean polyvinylidene chloride plastic. The layer of PVDC acts as a barrier layer for preventing the passage of gases and aromatic substances as is of particular significance in the packaging of food.
The thermoplastic foil is heated to a temperature of about 150.degree. C. and is deep drawn at this temperature in current practice. Thus a container is obtained which satisfies all requirements with regard to diffusion resistance but which is amendable to improvement in regard to its mechanical strength and stability. Because of the comparatively low strength and stability the known container has to have a comparatively large wall thickness to bear the given load or applied forces.
An improvement in regard to the mechanical strength and stability can be attained when the composite foil is subjected to cold forming. Because of that the plastic foil experiences a stretching which increases its strength. However the stretching can break the PVDC layer so that the diffusion resistance of the container manufactured no longer satisfies the requirements. The container made in the cold-forming process from the composite foil of the above described structure has not been found to be useful in practice.